Thermodynamic Analysis of Optimal Performance of Three Modes of Operation of Autothermal Chemical Looping Gasification

Abstract

A chemical looping gasification process comprising of fuel and air reactors (FR and AR) is thermodynamically analyzed under autothermal conditions. The analysis takes into account the incomplete carbon conversion in the FR. Depending on how the unburnt carbon in the FR is processed, 3 modes of operation are analyzed viz. (1) sending unburnt carbon to the AR, (2) removal of unburnt carbon from the process, and (3) recycle of unburnt carbon to the FR. Autothermal operating conditions are identified for each mode of operation. It has been shown that, for optimal performance, while mode 1 and mode 2 have to be operated with minimum flow of oxygen carrier (OC) and medium air flow, mode 3 has to be operated with maximum OC flow and minimum air flow. Performance results for mode 1 of operation at the optimal operation point are generalized to any solid fuel.